Shorter Catechism Q. 66. What is the reason annexed to the fifth commandment? A. The reason annexed to the fifth commandment is a promise of long life and prosperity (as far as it shall serve for God’s glory and their own good) to all such as keep this commandment.
Commentary: God incentivizes obedience to the fifth commandment by adding a promise to it. Consider two ways I could issue a command to my son. First, I could say, “Clean your room.” Second, I could say, “Clean your room, and when you are done, I will take you to your favorite restaurant (or buy you a toy, or take you to a Penguins game, etc.).” By adding a promise to the command, I am encouraging and motivating my son to do it. Moreover, I am saying that it is important to me that he keeps it and that I will be delighted by his doing it.
God wants us to keep this commandment and encourages us to do so by annexing “a promise of long life and prosperity.” The promise wouldn’t be much of a promise if it was merely long life. An extended life that is full of misery and hardship is more of a curse than a blessing. However, a life filled with joy and happiness is a wonderful blessing that is desired by all.
God promises a long prosperous life “to all such as keep this commandment.” This promise wasn’t just for Israelites under the Mosaic covenant living in the Promised Land of Canaan. The apostle Paul applies it to Christians regardless of where they live in the world (Eph. 6:1-3).
The promise must not be understood absolutely, that is, to imply that every godly child will experience a long, prosperous life. Nor should it be understood in a commercial sense as if a child can earn credits and turn them in for so many years of a good life. Hence, the catechism rightly qualifies the promise by noting that it is “as far it shall serve for God’s glory and their own good.” James Fisher suggests that if godly, obedient children die young “it is either to take them ‘away from the evil to come,’ Isa. 57:1; or to transplant them so much sooner ‘to a better country, that is, a heavenly,’ Heb. 11:16.”
Although God makes a similar promise to those who keep his commandments in general (i.e., to the faithful or covenant keepers), he attaches it to the fifth commandment, perhaps in part because he has ordained a natural and moral connection between it and a good, long life. A healthy family life is instrumental in becoming a responsible, productive adult, which in turn is instrumental in experiencing longevity and prosperity. Kevin DeYoung has noted: “Anyone in the social sciences field, whether liberal or conservative, has to acknowledge that study after study has shown that the best predictor for health as an adult and for making it through school, staying out of jail, keeping off drugs, and avoiding promiscuity—and whatever other pattern of social benefit—is what happens in the home.” Furthermore, strong families are instrumental in creating and maintaining a society that is conducive to human flourishing, which is also contributory to living well for a long time.